Defrost recycle device

Abstract

A defrost recycle apparatus and method for use with a temperature control system is provided. The temperature control system includes a heat transfer unit for removing heat from an enclosed space. The temperature control system automatically defrosts the heat transfer unit based upon a default defrost control strategy. After the termination of a defrost operation initiated according to the default defrost control strategy, the defrost recycle apparatus determines if the defrost operation was successful (completely defrosted the heat transfer unit) based upon two parameters associated with the defrost operation. In the preferred embodiment, the defrost recycle apparatus determines the success of the defrost operation based upon the temperature in the vicinity of the heat transfer unit after a predetermined period of time has elapsed after the termination of the defrost operation. If the defrost recycle operation determines that the defrost operation was not successful, the defrost recycle apparatus sends a force defrost signal to the temperature control system to initiate a recycle defrost operation.

What is claimed is: 
     
       1. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation, said defrost control device generating a termination indication when said defrost operation terminates, the apparatus comprising: a sensing means operatively connected with said defrost control device for sensing said termination indication;   a first measuring means for measuring one of a first or a second parameter associated with said defrost operation as a first measured parameter;   a second measuring means for measuring the other of said first or second parameters associated with said defrost operation as a second measured parameter;   said first measuring means, said second measuring means, and said sensing means being operatively connected; said second measuring means generating a measured second parameter value indicating said second measured parameter as measured substantially when said first measured parameter substantially equals a first predetermined value;   a comparing means operatively connected with said second measuring means for comparing said measured second parameter value with a second predetermined value; and   a signal generating means operatively connected with said comparing means for generating a premature termination signal when said measured second parameter value has a particular relationship with said second predetermined value.   
     
     
       2. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 1 wherein said first measuring means includes a temperature sensor, said first measured parameter being temperature, and said first predetermined value being a predetermined temperature. 
     
     
       3. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 2 wherein said defrost control device includes a heat transfer unit, said temperature sensor being configured to measure a heat transfer unit temperature within a predetermined distance of said heat transfer unit. 
     
     
       4. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 3 wherein said second measuring means includes a timer, said second measured parameter being time elapsed since said termination indication, and said second predetermined value being a predetermined period of time. 
     
     
       5. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 4 wherein said second measuring means is operatively connected with said temperature sensor. 
     
     
       6. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 3 wherein said temperature sensor includes a bi-metal switch positioned within said predetermined distance of said heat transfer unit. 
     
     
       7. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 6 wherein said bi-metal switch is configured to close when said heat transfer unit temperature substantially equals said predetermined temperature. 
     
     
       8. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 1 wherein said first measuring means includes a pressure sensor, said first measured parameter being pressure, and said first predetermined value being a predetermined pressure. 
     
     
       9. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 8 wherein said defrost control device includes a heat transfer unit, said pressure sensor being configured to measure pressure within said heat transfer unit. 
     
     
       10. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 9 wherein said second measuring means includes a timer, said second measured parameter being time elapsed since said termination indication, and said second predetermined value being a predetermined period of time. 
     
     
       11. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 10 wherein said second measuring means is operatively connected with said pressure sensor. 
     
     
       12. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 1 wherein said first measuring means includes a timer, said first measured parameter being time elapsed since said termination indication, and said first predetermined value being a predetermined period of time. 
     
     
       13. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 12 wherein said second measuring means includes a temperature sensor, said second measured parameter indicating temperature, and said second predetermined value being a predetermined temperature indication. 
     
     
       14. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 13 wherein said defrost control device includes a heat transfer unit, said temperature sensor being configured to generate a measured temperature indication in response to temperature within a predetermined distance of said heat transfer unit. 
     
     
       15. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 14 wherein said second measuring means is operatively connected with said timer. 
     
     
       16. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 14 wherein said temperature sensor includes a bi-metal switch positioned within said predetermined distance of said heat transfer unit, said measured temperature indication indicating whether said bi-metal switch is closed. 
     
     
       17. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 16 wherein said bi-metal switch is configured to close when said heat transfer unit temperature substantially equals a predetermined temperature. 
     
     
       18. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 12 wherein said second measuring means includes a pressure sensor, said second measured parameter indicating pressure, and said second predetermined value being a predetermined pressure indication. 
     
     
       19. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 18 wherein said defrost control device includes a heat transfer unit, said pressure sensor being configured to generate a measured pressure indication in response to pressure within said heat transfer unit. 
     
     
       20. An apparatus for use with a defrost control device for indicating an occurrence of a premature termination of a defrost operation as recited in claim 19 wherein said second measuring means is operatively connected with said timer. 
     
     
       21. An apparatus for use with a temperature control device for indicating an occurrence of a premature termination of a defrost operation, said temperature control device being configured to control temperature within an enclosed space, said temperature control device generating a termination indication when said defrost operation terminates, the apparatus comprising: a sensing means operatively connected with said temperature control device for sensing said termination indication;   a monitoring means operatively connected with said sensing means for monitoring a parameter associated with a condition within said enclosed space as a first measured parameter, and for monitoring elapsed time from said termination indication as a second measured parameter;   a first comparing means operatively connected with said monitoring means for comparing a selected parameter of said first measured parameter or said second measured parameter with a first predetermined value;   a second comparing means operatively connected with said first comparing means and said monitoring means, for comparing the other parameter of said first measured parameter or said second measured parameter than said selected parameter with a second predetermined value when said selected parameter substantially equals said first predetermined value; and   a signal generating means operatively connected with said second comparing means for generating a premature termination signal when said other parameter has a particular relationship with said second predetermined value.   
     
     
       22. A method for indicating an occurrence of a premature termination of a defrost operation, said defrost operation being performed by a defrost control device, said defrost control device generating a termination indication when said defrost operation terminates, the method comprising the steps of: sensing said termination indication;   measuring one of a first parameter and a second parameter associated with said defrost operation as a first measured parameter;   measuring the other of said first parameter and said second parameter than said first measured parameter as a second measured parameter;   generating a second measured parameter value indicating said second measured parameter as measured substantially when said first measured parameter substantially equals a first predetermined value;   comparing said second measured parameter value with a second predetermined value; and   generating a premature termination signal when said second measured parameter value has a particular relationship with said second predetermined value.   
     
     
       23. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 22 further comprising the step of setting a recycle flag when, after said comparing said second measured parameter value with said second predetermined value, said second measured parameter value has said particular relationship with said second predetermined value. 
     
     
       24. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 23 further comprising the step of clearing said recycle flag when, after said comparing said second measured parameter value with said second predetermined value, said second measured parameter value does not have said particular relationship with said second predetermined value. 
     
     
       25. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 24 wherein said generating said premature termination signal is not performed when said recycle flag is set. 
     
     
       26. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 22 wherein said first measured parameter is temperature and said first predetermined value is a predetermined temperature. 
     
     
       27. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 26 wherein said defrost control device includes a heat transfer unit, said step of measuring said first measured parameter including measuring a heat transfer unit temperature within a predetermined distance of said heat transfer unit. 
     
     
       28. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 27 wherein said second measured parameter is time elapsed since said termination indication, and said second predetermined value is a predetermined period of time. 
     
     
       29. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 27 wherein a bi-metal switch is positioned within said predetermined distance of said heat transfer unit, said step of measuring said first measured parameter including determining whether said bi-metal switch is closed. 
     
     
       30. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 22 wherein said first measured parameter is pressure, and said first predetermined value is a predetermined pressure. 
     
     
       31. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 30 wherein said defrost control device includes a heat transfer unit, said step of measuring said first measured parameter including measuring pressure within said heat transfer unit. 
     
     
       32. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 31 wherein said second measured parameter is time elapsed since said termination indication, and said second predetermined value is a predetermined period of time. 
     
     
       33. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 22 wherein said first measured parameter is time elapsed since said termination indication, and said first predetermined value is a predetermined period of time. 
     
     
       34. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 33 wherein said second measured parameter indicates temperature, and said second predetermined value is a predetermined temperature indication. 
     
     
       35. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 34 wherein said defrost control device includes a heat transfer unit, said step of measuring said second measured parameter including measuring a measured temperature indication representative of temperature within a predetermined distance of said heat transfer unit. 
     
     
       36. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 35 wherein a bi-metal switch is positioned within said predetermined distance of said heat transfer unit, said step of measuring said second measured parameter including determining whether said bi-metal switch is closed. 
     
     
       37. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 33 wherein said second measured parameter indicates pressure, and said second predetermined value is a predetermined pressure indication. 
     
     
       38. A method for indicating an occurrence of a premature termination of a defrost operation as recited in claim 37 wherein said defrost control device includes a heat transfer unit, said step of measuring a second measured parameter including measuring a measured pressure indication representative of pressure within said heat transfer unit.